Anecdote time. Never have I ever understood concepts through repetition alone. Grinding problems is for building patterns via using different input sets, not unlike ML. It is true that it "clicks" sometimes after a threshold and you actually understand it, but usually what grinding does is reinforce the algorithm without actually understanding it - e.g. surely you know that c squared equals a squared plus b squared, you've probably grinded that enough to memorize that equation. Can you prove it or at least explain why that equation is correct? Because i can't, not even after repeating it a million times. That's the difference between memorization and understanding.